Een harde onderhuidse bult

Background

Nodular fasciitis is a rare, benign soft tissue tumor in young adults on the arms or trunk.

Case description

A 24-year-old woman with previous pretibial melanoma in situ presented with a painless, rapidly growing subcutaneous hard swelling on the right forearm since two weeks. Ultrasound showed a subcutaneous, irregularly shaped, vascularized mass, suspicious for malignancy. Three days later, the swelling had subsided spontaneously. A new ultrasound showed a smaller, oval, sharply demarcated lesion with an inflammatory aspect. Histopathological-immunohistochemical examination of a biopsy showed a spindle cell lesion consisting of (myo)fibroblasts with some erythrocyte extravasation, consistent with nodular fasciitis. Three months later the nodule was resolved spontaneously without treatment.

Conclusion

Nodular fasciitis should be included in the differential diagnosis in case of hard, fast-growing, subcutaneous bumps in young adults. By ultrasound, it is difficult to differentiate from a malignant soft tissue tumor. A biopsy is necessary to confirm the diagnosis with certainty.

Conflict of interest and financial support: ICMJE forms provided by the authors are available online along with the full text of this article.